Of late, in technology decorating a surface of an article, there has been drawn attention to technology providing the functionality including photoluminescence obtained by formation of a thin film of metal or metal oxide, etc., UV protection, photo-catalyst function, electric conductivity, etc., in addition to or in replacement of a decoration based on printing or painting by conventional pigment-type or dye-type ink.
Especially, in order to obtain an advanced design, a demand of photoluminescent designs like metal tone, color plating tone or hologram tone has increased and there has been conventionally practiced a decorative technology in which such photoluminescent designs have been provided by spatter-processing articles.
However, in case where the designs are to be expressed in combination with the decorative layer by the conventional printing or painting, the decoration technology by the spatter-processing requires separate printing or painting step before or after the spattering step, which takes much time to thereby have poor workability.
In order to improve the decoration technology for providing photoluminescence by such two processes, there has been proposed water pressure transfer sheet (sometimes referred to as water pressure transfer film) used for obtaining a photoluminescent decorative layer by water pressure transfer (see Patent documents 1 to 6). Among them, all of the water pressure transfer sheets of the Patent documents 1 to 3 comprise water-soluble base substance film (Carrier film) and a metal layer formed on the water-soluble base substance film by vapor deposition directly or through a resin layer. Moreover, all of the water pressure transfer sheets of the Patent documents 4 to 6 comprise water-soluble base substance film (carrier film), a transparent resin layer formed on the water-soluble base substance film and a metal layer formed by vapor deposition or sputtering on the transparent resin layer and the metal layer and/or the transparent resin layer are embossed if needed. If the water pressure transfer is carried out on an article by using the water pressure transfer sheets of these Patent documents, a decorative layer having a hologram effect will be formed on the article. However, since the metal layer of the water pressure transfer sheet never swell by water, the metal layer has poor profile followability (attachment followability) relative to the three-dimensional surface of the article to be decorated by the water pressure transfer and therefore there have been a problem of being not able to manufacture a decorated article of high quality. Furthermore, although, in some case, the water pressure transfer sheet may be extended by cracks occurring in the metal layer by tensile stress generated when the water-soluble base substrate film swells and is expanded by water, even in this case, the cracks become uneven depending on the affinity with the extension characteristics of the resin layer and therefore, there occurs a problem of deteriorating the effect of the design.
In order to solve such a problem, there has been proposed water pressure transfer film having water-wettable transfer control layer between an embossed metal layer and water-soluble base substance film (see the Patent documents 7 to 12). Since the uniformity of the cracks formed in the metal layer is improved by the transfer control layer when the water pressure transfer film is expanded, the transfer film has the improvement on the followability to the three-dimensional surface of the article and the effect of the design. However, since the generated pattern of the cracks of the metal layer changes according to a pitch and a depth of the emboss (unevenness), if the uniformity of the cracks tries to be realized by controlling the pitch and the depth of the emboss, the freedom of design in the effect of the design (the hologram effect etc., for example) of photoluminescence resulting from embossing may be often restricted and it is required that this should be improved.
Although similar to the layer composition of the Patent document 7, there has been proposed a transfer film having no embossing composition (see the Patent document 13). Using the transfer film of such composition, the above problem resulting from the embossing will be able to be solved, but in case where the decorative layer of the water pressure transfer sheet has an additional print layer under the metal layer, even though an activating agent tries to be applied in order to activate the dried print layer to restore adhesiveness and/or swelling of the print layer, the metal layer prevents the activating agent from permeating the print layer. Thus, since the print layer is never wetted to thereby prevent the extension of the water pressure transfer sheet, the extensibility of the water pressure transfer film and the formation of the cracks in the metal layer become unstable and therefore there has been a problem of defect occurred regarding the followability of the decorative layer to the surface of the article (attachment followability or the effect of water pressure transfer) and the effect of the design. This problem similarly occurs in the conventional method disclosed in the Patent documents 7 through 12.
Furthermore, Since the extensibility of the water pressure transfer sheet is determined on the conditions of formation of the water-soluble base substrate film and the metal layer, the conditions where the action of extension of the water pressure transfer sheet during the water pressure transfer process is adjusted becomes restrictive. Thus, it is required to improve the producibility in view of this aspect.